Migraine.com is Health Union’s oldest and largest patient community, with more than 140,000 members on its Facebook page.

As an expecting mother, Facebook executive Danielle Salowski is experiencing firsthand what it’s like to engage with online patient communities.

She is a member of two Facebook groups for mothers, where she can have daily conversations on topics ranging from where to find the best baby products and prenatal yoga classes to how to pick a pediatrician, she said.

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“The community is incredibly open and active,” said Salowski, industry manager for Facebook Health. “I’ve met other expecting moms who have become ‘in-person’ friends in my area because of Facebook.”

Choosing to participate in online communities is a common behavior Facebook sees among new moms, whose use of the social platform increases by 348% by the end of a baby’s first year of life, noted Salowski.

According to a recent Wego Health survey of 433 members of online patient communities, 91% of respondents said those communities play a role in their health decisions. In addition, the patient advocacy network found that more of those patients (75%) share information privately through member-only groups, private phone calls, or emails, than publicly (61%) using Facebook posts, Tweets, or blog posts.

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Facebook itself has more than six million health-related groups, with more than 70 million members, noted Salowski. And there are companies like Health Union and MyHealthTeams that focus on building patient communities on Facebook, as well as other social channels and domains.

MyHealthTeams’ MyMSTeam has more than 85,000 members.

What are the pros and cons of hosting a patient community on a social platform versus a standalone website? It comes down to a trade-off between an external social platform’s simplicity and accessibility, and the complexity and flexibility of a website dedicated specifically to the patient community, said Amrita Bhowmick, chief community officer at Health Union, which has 15 condition-specific patient communities, each with their own Facebook page, Twitter handle, Google Plus page and website. Its most active patient communities include Migraine.com, MultipleSclerosis.net, and RheumatoidArthritis.net, which each have a Facebook reach of up to two million visitors per month.

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“Everyone’s on Facebook these days — you’re not asking them to go to a completely separate piece of real estate,” said Bhowmick. “But there are benefits on the other side. It might be more complex. [Users] need to sign up, learn how to use the site. However, you have a whole lot of flexibility. You can filter [and] set features that are most important to your members.”

There is also more flexibility when it comes to what users can post, added Bhowmick. “Sometimes, our community members will curse — they’re cursing at their condition, and it’s a really great way to vent,” she said. “Facebook will automatically filter those comments, which can then make them feel really badly.”

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MyHealthTeams, which has about one million members across 25 condition-specific patient communities, focuses on standalone websites and mobile apps to engage its members. It has Facebook and Twitter pages for each of the conditions as well, but mainly uses them to introduce its communities to potential members.

“Many of our members don’t want to be talking about their chronic condition on an open network such as Facebook but do feel comfortable on a network designed just for people with the same disease or condition as them,” said Eric Peacock, co-founder and CEO of MyHealthTeams.

According to Peacock, between 20% and 50% of its members return monthly to the MyHealthTeams websites and mobile social networks. Its Parkinson’s disease group is one of its most engaged groups, with roughly half of its more than 32,000 members participating in conversations every month.

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The sites and apps gather information such as when they were diagnosed, symptoms they have experienced, and the drugs they’re taking.

“A woman in her thirties who’s diagnosed with breast cancer and wants to get pregnant after chemo wants to connect with someone else who has dealt with or is dealing with this,” explained Peacock.

There’s no one size fits all solution, though, argued Tim Armand, president and co-founder of Health Union. “We analyze the market six months before entering it,” he said. “Then we have a read-and-react.”

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MyHealthTeams and Health Union have branded pharmaceutical ads in their networks. MyHealthTeams works with drugmakers on sponsored unbranded education initiatives, and Health Union posts sponsored unbranded content on its Facebook pages about events drugmakers hope to promote. They offer aggregated, de-identified patient data to pharmaceutical companies, executives at both companies said.

Both Health Union and MyHealthTeams have worked with drugmakers to do research on how patients feel about the drugs they’re taking and how to match them with clinical trials.

“We sit between the patients wanting to find trials and sponsors wanting to find patients,” said Armand. “We help companies understand in the development process what kinds of outcomes would be meaningful to patients from the beginning, rather than when you have a product on the market.”